52 INTRODUCTORY — THE CONSTITUENTS OF MILK. 



butyrate. Ethyl butyrate is a volatile liquid of a smell recalling 

 the odour of pine apples. 



Caproic Acid, CH3.CH2.CH2.CH2.CH2COOH.— Koefoed Las 

 proved that the caproic acid of the fat of milk is normal. This 

 acid is an oily liquid with an unpleasant goat-like smell. It 

 boils at 205° C, solidifies at —18° C, and melts at —1-5°. Its 

 density at 0° is 0'9446 according to Zander. 



It hardly mixes with water, is extracted by ether from an 

 aqueous solution, and possesses considerable solubility in the 

 mixed higher fatty acids of milk fat. From a dilute aqueous 

 solution it distils four times as fast as water. 



The calcium salt differs from calcium butyrate by increasing 

 in solubility on heating; 100 parts of water dissolve at 11° to 

 12° 2-36 parts, at 17-5° 2-58 parts, and at 18-5° 271 parts of 

 calcium caproate. It crystallises in needles. The barium salt 

 dissolves in 100 parts of water to the extent of 12 parts at 11° to 

 12°, and the solubility decreases on heating. 



Caprylic Acid, CyHjjCOOH. — This acid crystallises in plates 

 or needles melting at 16 '5° C, and boils at about 236° C. It 

 has a faint unpleasant odour of sweat, and a sharp rancid taste ; 

 it is difficultly soluble even in hot water, from which it crystal- 

 lises in plates. From dilute solutions it distils eight times as 

 fast as water. 



Barium caprylate crystallises in anhydrous plates, and is 

 soluble to the extent of 6 parts in 100 parts of water at 20° C. 

 The calcium salt crystallises in long thin needles, and is less 

 soluble than the barium salt — 0'6 part per 100. 



Caprio Acid, Cc,Hj,|COOH. — This acid has a faint goat-like 

 odour, and is only very slightly soluble in water. It crystallises 

 in brilliant plates, melting at 30° C. ; it boils at 268° to 270°. 

 The barium and calcium salts are nearly insoluble in water, 

 even on boiling, and the salts of the alkalies are the only ones 

 appreciably soluble. 



Laurie Acid, CuHjjCOOH. — The acid is solid at ordinary 

 temperatures, and is not soluble to any extent in water ; it 

 passes over to a very appreciable extent when distilled with steam. 

 It crystallises from alcohol in needles, melting at 43-6° C. It 

 cannot be distilled without decomposition at the atmospheric 

 pressure, but at 100 mm. it has a boiling point of 225° C. The 

 salts of the alkali metals yielded by the acids previously described 

 are soluble in strong salt solution ; the laurates of sodium and 

 potassium are, however, precipitated by strong sodium chloride 

 solutions, but not by weaker ones. Laurie acid is a leading 

 constituent of cocoa-nut and palm-nut oils. 



Myristic Acid, C^gH^yCOOH. — This acid crystallises in 

 laminae melting at 53 '8° C. and boils at 250-5° under 100 mm„ 



